Treatment of hydrocarbon oils



TREATMENT OF" HYDROCARBON OILS Original FiledFeb. 11, 1931 F RACTIONATOR FURNACE INVE NTOR GUSTAV EGLOF F BY Z Q%@ ATTO RNEY Patented Jan. 4, 1938 UNITED STATES arc n Pier QFFECE- TREATMENT OF HYDROCARBON OILS Application February 11, 1931, Serial No. 514,919

, Renewed May 15, 1935 4 Claims.

This invention relates to the treatment of hydro-carbon oils and refers particularly to the conversion of relatively heavy hydrocarbon oils into substantial yields of lighter and more valu- 5 able products and reduction of the relatively heavy residual products of the conversion to coke or carbonaceous material. v

Primarily the invention comprises subjecting hydrocarbon oil to conversion conditions whereby products both lighter and heavier than the charging stock are preferably produced and subjecting the relatively heavy residual products to reheating and subsequent reduction under reduced pressure to substantially dry carbonaceous material.

As a feature of the invention the relatively heavy components of the vapors evolved by distillation of the residual oil from the cracking operation may be reheated either alone or together with residual liquid from the cracking system and are preferably introduced into the residuum redistilling zone to assist in the substantial devolatilization of the residual product of the system usually to effect its substantial reduction to coke or carbonaceous material.

The attached diagrammatic drawing illustrates one form of. cracking system in which the principles of the present invention have been incorporated. The drawing and the following description will more clearly illustrate the novelty and features of the present invention.

Raw oil charging stock may be supplied through line i and valve 2 to pump 3 to be fed through line 4, valve 5, preheating coil 6, line 1', valve 8 and line 9 into fractionator H). Preheating coil 6 may be disposed within fractionator H and the raw oil fed therethrough may be preheated by indirect contact with the relatively hot vapors in this zone. Reflux condensate resulting from fractionation of the vapors and condensation of their relatively heavy components in fractionator I! may pass therefrom through line l2 and valve Hi to pump M from which it may be fed through line and may, if desired, be supplied, all or in part, through line 9 and valve Hi to fractionator l3 together with the preheated raw oil from line I. The oil thus supplied to fractionator Il! may be preheated by direct contact with the relatively hot ascending vapors in this zone assisting their fractionation and passing together with their 50 relatively heavy condensed components through line ll and valve !8 to pump I9 from which the combined feed may be supplied through line 23 and valve 2i to heating element 22.

Heating element 22 may be located in any suitable form of furnace 23 and the oil supplied thereto may be heated to the desired conversion temperature preferably under a substantial superatmospheric pressure. The heated oil may pass through line 24 and valve 25 to reaction chamber 26 also preferably maintained under substantial super-atmospheric pressure, which may be either substantially equalized with or lower than that employed in heating element 22. Separation of vapors and non-vaporized residual liquid may take place in chamber 26. The vapors may pass through line 2! andvalve 28 to fractionator Hi from which their relatively heavy insufficiently converted components may be returned as condensate to heating element 22 for reconversion, as already described. The relatively light components of the fractionated vapors withdrawn from fractionator l0 through line 29 and valve 30, may be subjected to condensation and cooling in condenser 3|, condensed distillate and uncondensable gas from which may pass through line 32 and valve 33 to be collected in receiver 34. Uncondensable gas may be released from receiver 34 through line 35 and valve 36. Distillate may be withdrawn through line 3'! and valve 38. A portion of the distillate from receiver 34 may, if desired, be withdrawn through line 39 and valve ll] and recirculated by means of. pump 4| through line 42 and valve 43 to fractionator II] to assist fractionation in this zone.

Residual liquid withdrawn from reaction chamber 26 through line 44 may pass, all or in part, through valve 45, line 6|, valve 62 and line 55 into residuum distilling and coking chamber 46. Any desired portion or all of the residual liquid instead of passing direct to chamber 46 may pass through line 41, valve 48, pump 69, line 50, valve 5| and line IE to heating element 53 which may be located in any suitable form of furnace 54 and in which any desired quantity of additional heat may be supplied to the oil fed therethrough. Residual oil alone may, if desired, be supplied to heating element 53 or, if so desired, this product may be mixed prior to its introduction into the heating element with all or a portion of the reflux condensate from fractionator II which may be supplied from pump l4 through line l5 and valve 52.

Another method of operation embodied by the present invention permits reheating of substantially all or a portion of the reflux condensate from fractionator ll in heating element 53 without the previous admixture of this product with any substantial quantity of residual liquid from chamber 23. In this latter case the residual liquid from chamber 26 may pass directly to chamber 46, as already described. Heated oil from heating element 53 comprising either residual liquid or'reflux condensate or residual liquid and reflux condensate, as the case may be, may pass through line 55 and valve 56 mixing in this line with that portion, if any, of the residual liquid from chamber 26 fed directly through this line and passing therewith into chamber 46.

Chamber 46 is preferably maintained under reduced pressure relative to that employed in chamber 25 and the heat supplied to the residual oil introduced into this zone, whether supplied directly to the residual oil in heating element 53 or supplied by admixture of the residual oil with reheated reflux condensate or supplied partially in both manners is sufficient in any case to effect its redistillation and substantial reduction in chamber 46 to coke or carbonaceous material.

It will be understood that if desired two or more chambers similar to chamber 46 may be employed either alternately or in parallel to permit prolonged operation of the process although for the sake of simplicity this arrangement is not illustrated in the drawing.

Chamber 46 may be provided with a drain line 63 and valve 64.. Vapors from chamber 46 may pass throughline 65 and valve 65 to fractionator H where their relatively heavy components may be condensed and returned, as already described, either to fractionator H1 or to heating element 53 or in part to both. The relatively light components of the fractionated vapors from fractionator 6 may pass through line 61- and valve 68, to be subjected to condensation and cooling in condenser 69, products from which may pass through line 10 and valve H into receiver 12. Uncondensable gas may be released from receiver 12 through line 5! and valve 58. Distillate may be withdrawn through line 59 and valve 60.

Pressures employed within the system may range from subatmospheric to superatmospheric of the various elements.

pressures as high as 2000 pounds per square inch or more. Substantially equalized pressure may be employed throughout the entire system or differential pressures may be utilized between any As already stated reduced pressure relative to that employed in the reaction chamber of the cracking system is preferably utilized in the residuum redistilling or coking zone. Conversion'temperatures employed may range from 750 to 1200 F.-, more or less.

As a specific example ofoperating conditions which may be employed in the process of the apparatus above described, a 22-24" A. P. I. gravity fuel oil is subjected in the heating element of the cracking system to a temperature of approximately 915 F. under a superatmospheric pressure of about 200 pounds per square inch. Succeeding portions of the cracking system comprising the reaction chamber, fractionator and the condensing and collecting equipment are maintained undera pressure substantially equalized with that employed. in the heating element. A mixtureof substantially all of the residual oil from the reaction chamber and about one-half, of the reflux condensate from the fractionator of the residuum distilling system is subjected in the reheating element to a temperature of approximately875 F. under a superatmospheric pressure of about 300 pounds per square inch and the reheated mixture is introduced into the residuum redistilling or coking chamber in which it is reduced to substantially dry coke or carbonaceous material.

The operation above outlined may yield approximately percent of motor fuel having an anti-knock value approximately equivalent to a blend of 50 percent benzol and 50 percent Pennsylvania straight-run gasoline. About 12 percent of pressure distillate bottoms and approximately 15 percent of coke or carbonaceous material are also produced, the only other product being about 8 percent of fixed gas.

In general when oils of lighter gravity are processed, increased yields of liquid products and decreased yields of coke may be expected and viceversa, this of course being also dependent, in part, upon the conversion temperatures and pressures employed. To generalize still further when the residual oil withdrawn from the reaction chamber of the cracking system is a relatively light gravity clean product containing little suspending coke or carbonaceous material it may be passed through the reheating element without the prior admixture of reflux condensate from the fractionator of the residuum distilling system. On the other hand, When this residual product is a relatively heavy material containing substantial amounts of suspended carbonaceous material and bottom settlings it is preferably supplied directly to the coking chamber and additional heat for its reduction to coke may be supplied by reflux condensate-from the fractionator of the residuum distilling system which may be reheated alone.

I claim as my invention:

1. A hydrocarbon cracking process which comprises passing the charging oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under r pressure, discharging. the heated oil into a separating zone and separating the same therein into vapors and unvaporized oil, removing the unvaporized oil from the separating zone and passing a portion thereof directly to a flashing zone maintained under lower pressure than the separating zone, removing the vapors from the flashing zone and dephlegmating the same to condense heavier fractions thereof, combining resultant reflux condensate with the remaining portion of the unvaporized oil removed from the separating zone, passing the resultant mixture through a second heating zone maintained at conversion temperature, and then discharging the heated mixture into said flashing zone.

2. A process for cracking hydrocarbon oil comprising passing the oil through a heating coil wherein it is raised to cracking temperature, thence delivering the same to a high pressure reaction zone, passing residual products from said high pressure reaction zone to a low pressure flash zone, diverting a portion of the residual products passing from said high pressure reaction zone to said low pressure flash still to and through a second heating coil and thence into the low pressure flash still, separately taking oflz vapors from said reaction zone and said low pressure flash still, subjecting such vapors to fractionation and uniting a portion of the reflux condensate formed by fractionation of the vapors with that portion of the residual oil passing through the second-mentioned heating coil.

3. A process for cracking hydrocarbon oil comprising passing the oil through a heating coil wherein it is raised to cracking temperature, thence delivering the same to a high pressure reaction zone, passing residual products from said high pressure reaction zone to a low pressure flash zone, diverting a portion of the residual products passing from said high pressure reaction zone to said low pressure flash still to and through a second heating coil and thence into the low pressure flash still, separately taking off vapors from said reaction zone and said low pressure flash still, subjecting such vapors to fractionation in heat exchange relation with charging oil for the process, and uniting a portion of the reflux condensate formed by fractionation of the vapors with that portion of the residual oil passing through the second mentioned heating coil.

4. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil, separating the heated products into vapors and unvaporized oil in a separating zone maintained under pressure, discharging a portion of said unvaporized oil directly from the separating zone into a low pressure flash still, passing another portion of said unvaporized oil from the separating zone through a second heating coil and thence into the low pressure flash still, fractionating the first-named vapors and the vapors from the flash still, passing resultant reflux condensate through the second heating coil together with said other portion of the unvaporized oil, and finally condensing the fractionated vapors.

GUSTAV EGLOFF. 

